1. Field of the Invention
The present invention relates to a technique for monitoring an abstract state in a presence service.
2. Description of Related Art
There have been known presence systems for managing users' state. For example, patent document 1 (Japanese Patent Application Laid Open No. 2004-246397) describes a presence system that uses a buddy list (or a state-monitored person list).
A presence system is one of names of a presence service that generally represents a system for managing states of individual users, devices, services, concepts or the like, and the basic architecture is shown in Request For Comment (RFC) 2778.
A presence system includes presentities, watchers, and a presence servicing section.
A presentity stores the state (or presence information) of a person who provides state information. Specifically, a presentity is a terminal device that stores presence information of an entity that provides state information.
A watcher provides presence information stored by the presentity to a person who receives state information. Specifically, a watcher is a terminal device that receives presence information stored by the presentity.
The watcher receives presence information of a certain presentity specified by the watcher, not all presetities' presence information. A presentity specified by a watcher is called a buddy (a target of monitoring). The watcher creates a buddy list indicating buddies (or a state-monitored entity list) in order to obtain presence information for the buddies.
The presence servicing section delivers presence information about the buddies indicated in the buddy list to the watcher.
Patent document 2 (Japanese Patent Laid Open No. 2002-091893) describes a workflow system in which a plurality of terminal devices which are interconnected through a network updates one electronic file in turn.
Also, Semantic Web has been known as a technique for representing relationships among presentities. Basic technologies for realizing the Semantic Web include RDF, RDF schema, and/or OWL. The RDF is representation of meta data that can be processed by machines; the RDF schema provides means for defining vocabulary (class and property); and the OWL is a technique that enables more detailed definition of vocabulary and also enables inference for allowing association and merging of a plurality of schemata.
Patent document 3 (Japanese Patent Laid Open No. 2004-029925) discloses a techniques including means for a suspicious person monitoring device to receive suspicious person monitoring request information from a user; first storage means for storing monitoring timer information that corresponds to the suspicious person monitoring request; means for extracting monitoring timer information corresponding to the suspicious person monitoring request from the first storage means and setting a monitoring timer that is based on monitoring timer information; second storage means for storing empty home information corresponding to the suspicious person monitoring request information; and means for, when time-out of the monitoring timer is detected, generating suspicious person presence information based on the suspicious person monitoring request information and empty home information corresponding to the suspicious person monitoring request information extracted from the second storage means, and sending the suspicious person presence information to the user.
Other references relating to the above conventional techniques are: IETF RFC2778 (http://www.ietf.org/rfc/rfc2778.txt), RDF Resource Description Framework (RDF) Concepts and Abstract Syntax (http://www.w3.org/TR/rdf-concepts/), RDF Vocabulary Description Language (http://www.w3/org/TR/rdf-schema/), OWL Web Ontology Language Overview (http://www.w3.org/TR/owl-features/).
However, the above-mentioned conventional techniques have problems as follows.
To obtain an abstract state, it is necessary to estimate the abstract state. To estimate the state, it is required to obtain, calculate, and combine states of elements that constitute the abstract state.
To be specific, following two operations are required:
(1) Elements that constitute an abstract state are appropriately selected. For example, a user may select a resident A of a house as an element that makes up the state of the house. When the house resident A goes out, the user selects a fixed phone in the house.
(2) A method for calculating an abstract state is appropriately selected. For example, in order to derive the state of the house, the user selects the calculation method 1 from state calculation methods 1 and 2 in accordance with the resident A's state.
A problem is that automation of these processes by combining conventional techniques results in an estimated abstract state that does not correspond with an actual situation. Ror example, assume that “resident A” and “a monitoring system” are extracted as elements constituting the abstract state of the house and a calculation method is: “When position information for resident A represents the house, the state of the house is assumed to be ‘safe’, otherwise ‘unsafe’”. Assume further that the monitoring system is activated when the resident A leaves the house. In this case, a combination of conventional techniques would determine the state of the house to be “unsafe” when position information of “resident A” indicates somewhere other than the house. However, since the monitoring system is on, the state of the house must be “safe”. Thus the estimated abstract state does not correspond with the actual situation.
Also, even if suspicious person presence information (one of abstract states) disclosed in patent document 3 is generated based on rules, suspicious person presence information that does not correspond with an actual situation will be calculated because it is not possible to dynamically select a method for calculating suspicious person presence information.
That is, a method for calculating suspicious person presence information cannot be selected in response to update of empty home information. In addition, because selection of a method for calculating suspicious person presence information is not automatically made in response to addition of a new door or other equipment or elimination thereof, calculation might become impossible. For instance, since the method for calculating suspicious person presence information disclosed in patent document 3 is fixedly selected, only binary calculation, e.g., opening and closing of a door, is possible and suspicious person presence information cannot be calculated from equipment that possesses three or more values. Specifically, it is impossible to select a method for calculating suspicious person presence information in response to update of the state (e.g., opening and closing) of floor equipment, such as a door.